基于靶向细胞周期依赖性激酶CDK4/6的多模态分子影像技术监测乳腺癌抗肿瘤药物疗效的研究

Compared with RECIST criteria, 18F-FDG PET/CT imaging can assess the therapeutic response within one week after anti-tumor treatment, significantly shorten the cycle of the evaluation, and timely adjust the regimens. However, 18F-FDG PET/CT cannot directly monitor the target of drug, and has a relative low specificity. Therefore, a new approach is needed to specifically monitor the target of drug based on multimodal molecular imaging, which could visualize the target and assess the efficacy as early and accurately as possible. The dysregulation of cell cycle is a characteristic manifestation of tumor. Abnormal activation of the cell cycle-dependent kinase CDK4/6 promotes the proliferation of breast cancer. Palbociclib, a CDK4/6 inhibitor, has been approved as a novel drug using in the treatment of breast cancer. Based on a series of our previous studies using luciferase reporters for monitoring CDKs activity and cell cycle to evaluate therapeutic response of anti-tumor drugs, a set of multimodal molecular probes targeting CDK4/6 activity will be constructed in this project. The reflection and visualization of the CDK4/6 activity and cell cycle by those molecular probes will be tested and verified repeated in vitro and in vivo. Importantly, we will pursuit the study on multimodal molecular imaging for monitoring the anti-breast cancer efficacy of CDK4/6 inhibitors, optimizing the treatment options. This study aims to establish a system of multimodal molecular imaging to monitor the activity of target and evaluate the efficacy of anti-tumor drug.

基于18F-FDG的PET/CT分子影像技术，与RECIST标准相比，治疗后1周内就可以判断疗效，显著地缩短了评价时间、可及时调整用药，但是该技术不能监测药物靶点、特异性较差。鉴于此，基于可视化药物靶点的多模态分子影像技术能够特异性地监测靶点，还可以尽早、精准地评估抗肿瘤疗效。细胞周期异常是肿瘤的重要特征，其依赖性激酶CDK4/6的活性增强促进乳腺癌细胞的增殖。CDK4/6抑制剂Palbociclib是治疗乳腺癌的新型靶向药物，已在国内外获批上市。本项目在应用细胞周期报告基因监测CDKs和抗肿瘤疗效系列研究的基础上，拟构建靶向CDK4/6活性的多模态分子探针，通过在乳腺癌细胞和小动物反复验证，实现CDK4/6活性及细胞周期的可视化。本项目将进一步监测细胞周期药物的抗乳腺癌疗效，优化治疗方案，旨在建立多模态分子影像技术监测靶点活性和评价抗肿瘤药物疗效的体系。

目前通过测量肿瘤病灶的大小来评价抗肿瘤药物的疗效，但是该技术不能监测药物靶点、特异性较差。而基于可视化药物靶点的分子影像技术能够特异性地监测靶点，尽早、精准地评估抗肿瘤疗效。细胞周期异常是肿瘤的重要特征，细胞周期依赖性激酶CDK4/6的抑制剂如Palbociclib（帕博西尼）可阻碍乳腺癌细胞的增殖，有显著的抗癌疗效。本课题构建了两个优势互补的靶向CDK4/6活性的分子影像探针CPP30-Lipo/CDKACT4及Palbociclib-ICG。首先在乳腺癌细胞裂解液水平验证了CDKACT4多肽传感器能有效反应CDK4/6激酶活性，并在活细胞水平验证了 CPP30穿膜肽的细胞穿膜特性，及CPP30-Lipo/CDKACT4分子探针的生物相容性及对乳腺癌MCF-7细胞的靶向特异性。随后在细胞水平，验证了CPP30-Lipo/CDKACT4分子探针可以监测细胞周期进程，及CDK4激酶活性差异，建立了分子影像信号—细胞周期—CDK4活性之间的准确关联。当用不同浓度的帕博西尼处理细胞时，CPP30-Lipo/CDKACT4探针的分子影像信号随之变化，在细胞水平建立分子影像信号-帕博西尼疗效的关联。为模拟临床应用，成功构建管腔型乳腺癌异体移植小鼠模型，用CPP30-Lipo/CDKACT4分子探针在活体小动物水平监测帕博西尼药物疗效，建立了在体分子影像信号改变与G1期调控蛋白、药物疗效之间的关联。为更好满足在体成像及临床转化需求，优化探针信号的穿透深度、减少自荧光背景等，另外合成了极具临床转化潜能的小分子荧光探针Palbociclib-ICG。目前已完成在细胞水平监测CDK4/6活性的验证及在动物水平对帕博西尼抑制作用监测的初步验证。本项目培养博士生9名，硕士生21名，引进海外博士后 1 名；在相关的国内外杂志发表论文 11 篇，其中 SCI 收录 10篇，影响因子10分以上的2篇，北大核心收录1篇；申请国家发明项专利7项，授权国家发明专利 2项；获中国抗癌协会科技奖二等奖、辽宁省科学技术进步奖二等奖、厦门市科学技术进步奖二等奖各 1 项；获厦门市十大医疗创新技术1项。本项目用分子影像的方法可视化监测细胞周期药物的抗乳腺癌疗效，可优化治疗方案，并探索抗乳腺癌疗效评估的临床转化，建立起分子影像技术监测靶点活性和评价抗肿瘤药物疗效的体系。